LED array with metalens for adaptive lighting

ABSTRACT

An adaptive lighting system comprises an array of independently controllable LEDs, and a metalens positioned to collimate, focus, or otherwise redirect light emitted by the array of LEDs. The adaptive lighting system may optionally include a pre-collimator positioned in the optical path between the array of LEDs and the metalens.

FIELD OF THE INVENTION

The present disclosure relates to adaptive illumination using lightemitting diodes (LEDs) in combination with a metalens to provideadaptive light sources, for example for camera flash, virtual reality(VR), or augmented reality (AR) systems.

BACKGROUND

The term “light emitting diode” as used in this description is intendedto include laser diodes (e.g., vertical cavity surface emitting lasers,VCSELs) as well as light emitting diodes that are not lasers. The highefficiency of LEDs compared to conventional filament lightbulbs andflorescent lights as well as improved manufacturing capability has ledto their vastly increased use in a wide range of lighting applications.The compact nature, low power, and controllability of LEDs has likewiseled to their use as light sources in a variety of electronic devicessuch as cameras and smart phones.

SUMMARY

An adaptive lighting system comprises an array of independentlycontrollable LEDs, and a metalens positioned to collimate, focus, orotherwise redirect light emitted by the array of LEDs. The adaptivelighting system may optionally include a pre-collimator positioned inthe optical path between the array of LEDs and the metalens.

These and other embodiments, features and advantages of the presentinvention will become more apparent to those skilled in the art whentaken with reference to the following more detailed description of theinvention in conjunction with the accompanying drawings that are firstbriefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of an example adaptive lightingsystem comprising an LED array and a metalens.

FIG. 2 shows a top view of the LED array in the example adaptivelighting system of FIG. 1 .

FIG. 3 shows an example of a possible arrangement of pillars(nano-cylinders) in an array of nanoantennas in a metasurface in ametalens, such as for example the metalens in the example adaptivelighting system of FIG. 1 .

FIG. 4 shows a cross-sectional view of an example adaptive lightingsystem comprising an LED array, a pre-collimator, and a metalens.

FIG. 5 shows a cross-sectional view of another example adaptive lightingsystem comprising an LED array, a pre-collimator, and a metalens.

FIG. 6 shows a plot of calculated transmission versus angle of incidencefor an example metalens.

FIG. 7 shows another plot of calculated transmission versus angle ofincidence for the example metalens of FIG. 6 .

FIG. 8 shows a plot of reflectance as a function of angle of incidencefor the example metalens of FIG. 6 .

FIG. 9 schematically illustrates an example camera flash systemcomprising an adaptive illumination system.

FIG. 10 schematically illustrates an example AR/VR system that includesan adaptive illumination system.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings, in which identical reference numbers refer to like elementsthroughout the different figures. The drawings, which are notnecessarily to scale, depict selective embodiments and are not intendedto limit the scope of the invention. The detailed descriptionillustrates by way of example, not by way of limitation, the principlesof the invention.

An array of independently operable LEDs may be used in combination witha lens, lens system, or other optical system to provide adaptiveillumination, that is, illumination that may be varied in intensity,color, direction, and/or spatial location depending for example oncharacteristics of objects or a scene to be illuminated. Such adaptiveillumination is increasingly important for automotive, mobile devicecamera, VR, and AR applications. In these applications the dimensions,especially the height of the light source and associated optics (e.g.,lenses), may be an important design parameter.

In mobile devices such as smart phones or tablets, it may be desirableto have cameras provide different fields of view, varying between 40°and 120° for instance for a smart phone. An adaptive illumination unitmatching such a field of view should optimize light throughput whilefitting into a limited volume. A lens used for such illumination doesnot need to have perfect imaging properties since resolutionspecifications are not as high as required for imaging applications.Efficiency is preferred over traditional imaging quality characteristicperformance parameters such as those based on a modulation transferfunctions.

This disclosure describes adaptive lighting systems comprising an LEDarray in combination with a metalens. As further described below, ametalens comprises a nano-structured surface (a metasurface) or ananostructured structure (metastructure) designed to perform a lens-likefunction (e.g., act as a converging lens). Advantageously, a metalensmay have a thin flat geometry, which facilitates a compact devicedesign. The LED array may comprise independently operable discrete LEDsarranged as an array. Alternatively, the LED array may comprise one ormore segmented monolithic LEDs in which the segments may beindependently operable as LEDs. By “segmented monolithic LED” thisdisclosure refers to a monolithic semiconductor diode structure in whichtrenches passing partially but not entirely through the semiconductordiode structure define electrically isolated segments. The electricallyisolated segments remain physically connected to each other by portionsof the semiconductor structure.

FIG. 1 shows a cross-sectional view of an example adaptive lightingsystem 100 comprising an LED array 110 disposed in a housing 120. In theillustrated example LED array 110 is a monolithic LED device comprisingindependently operable LED segments S11, S12, S13, S14, and S15. Ametalens 130 attached to housing 120 redirects (for example, collimatesor focuses) light rays 115 emitted by the LED array. Adaptive lightingsystem 100 may provide illumination over a field of view of, forexample, about 40° to about 80°, or to about 120°.

FIG. 2 shows a top view of LED array 110, which in this examplecomprises 25 independently operable LED segments arranged in a square5×5 array and identified by their location in the array by row andcolumn as S(row, column) running from S11 to S55. More generally, LEDarray 110 may be for example a rectangular array or may approximate anon-rectangular (e.g., circular or oval) shape. Any suitable sized arraymay be used, for example a 3×3 array, a 5×5 array (as shown), a 7×7array, or a 15×21 array. The LED segments in the array can be of thesame size, or of different sizes. For example, the central segment couldbe chosen to be larger than peripheral segments. The array may havedimensions in the plane of the array of, for example, about 1.5 mm×1.5mm to about 3 mm×3 mm.

The LED segments in array 110 may have dimensions in the plane of thearray of, for example, about 5 microns to about 500 microns. Thesegments may be separated from their closest neighbors by, for example,5 microns or more. The segments may be positioned within a distance ofeach other sufficient to both present a substantially uniform visualappearance and to provide a substantially uniform light beam. Thisdistance can be selected so that the segments are separated by no morethan a Rayleigh limit distance calculated for a user at a normaldistance from the light source.

Each segment in LED array 110 may be a single color, with differentsegments emitting different colors (e.g., some segments emitting whitelight and other segments emitting red light). Different color segmentscan be interleaved. Segments of the same color may be grouped. Groups ofone color of segment may be interleaved with groups of other colors.Independent operation of the segments allows the color of light emittedby the array to be tuned.

Each segment comprises a semiconductor light emitting diode, andoptionally a wavelength converting structure that absorbs light emittedby the semiconducting light emitting diode and emits light of a longerwavelength. The semiconductor light emitting diodes maybe formed forexample from II-VI, III-V, or other semiconductor material systems andmay be configured to emit, for example, ultraviolet, visible, orinfrared light, depending on the application.

The wavelength converting structures include one or more wavelengthconverting materials which may be, for example, conventional phosphors,ceramic phosphors, organic phosphors, quantum dots, organicsemiconductors, II-VI or III-V semiconductors, II-VI or III-Vsemiconductor quantum dots or nanocrystals, dyes, polymers, or othermaterials that luminesce. Phosphor or other wavelength convertingmaterials may be dispersed as luminescent particles in a binder materialsuch as a silicone, for example, to form a wavelength convertingstructure. The wavelength converting structure may include lightscattering or light diffusing elements, such as for example TiO₂. Thewavelength converting structures may be a monolithic element coveringmultiple or all semiconductor light emitting diodes in an array, or maybe structured into separate segments, each attached to a correspondingsemiconductor light emitting diode. Gaps between these separate segmentsof the wavelength conversion structure may be filled with opticallyreflective material to confine light emission from each segment to thissegment only.

In operation of adaptive lighting system 100, individual segments in LEDarray 110 may be operated to provide illumination adapted for aparticular purpose. For example, adaptive lighting system 100 mayprovide illumination that varies by color and/or intensity across anilluminated scene or object and/or is aimed in a desired direction. Acontroller can be configured to receive data indicating locations andcolor characteristics of objects or persons in a scene and based on thatinformation control LED array 110 to provide illumination adapted to thescene. Such data can be provided for example by an image sensor, oroptical (e.g. laser scanning) or non-optical (e.g. millimeter radar)sensors.

For an application such as a flash, for example, the total emittedoptical power of the LEDs may be, for example, about 0.1 W to about 10W.

Referring again to FIG. 1 , metalens 130 may be planar, as shown, andmay have dimensions significantly larger than those of the LED array asmeasured in a plane parallel to the plane of the LED array. For example,metalens 130 may be 2 to 3 times the size of the LED array. The metalensis designed such that all light emitted from a specific LED segment inthe LED array reaches a predefined region in the far field.

The field of view illuminated by adaptive lighting system 100 may becontrolled by selecting the number and location of LEDs in array 110that are operated to provide the illumination. In case a small field ofview is needed, for instance 40°, only the central LED segments might beneeded, while for a large field of view (for instance 120°) all LEDsegments could be switched on.

As noted above, metalens 130 is or comprises one or more metasurfaces ormetastructures arranged so that metalens 130 functions as a lens, e.g.,it focuses, collimates, or otherwise redirects rays of light incident onit from the LED array. Metalens 130 may function as a converging lens,for example. Metasurfaces are surfaces in which physical structureand/or chemical composition vary on a length scale that is typicallyless than a micron, i.e., they are nanostructured. Similarly,metastructures are structures in which physical structure and/orchemical composition vary on a length scale typically less than amicron. Metasurfaces and metastructures may be designed to provideparticular optical functions and effects.

Metalens 130 comprises at least a first array of nano-scale antennas(nanoantennas) arranged, for example, as a metasurface in a planeparallel to the plane of the LED array. Each nanoantenna typically hasdimensions in the plane of the array less than or equal to a free spacewavelength of light emitted by the LED array. The nanoantennas havestructural, chemical, and/or optical properties that vary with thespatial location of the nanoantennas to affect phase and amplitude oflight emitted by the LED array through the metalens in a spatiallyvarying manner that focuses, collimates, or otherwise redirects thelight emitted by the LED array.

For example, the nanoantennas may be arranged to form nano-gratings inconcentric rings about a central optical axis of the metalens. The widthof each concentric ring in the plane of the metalens decreases as afunction of radial distance from the central optical axis. Towards theouter edge of the metalens, the width of each ring can be for example inthe range of 700 nm-1000 nm while towards the center of the metalens thewidth can be for example 1500 nm-5000 nm. The spacing betweennanoantennas also changes as a function of the radial position withnanoantennas towards the edges arranged with a pitch of, for example,220 nm-250 nm and nanoantennas toward the center arranged with a pitchis closer to 250 nm. That is, the pitch may decrease with increasingradial distance from the central axis.

The nanoantennas may be or comprise structures having pillar(nano-cylinder) shapes, for example. For example, metalens 130 maycomprise one or more periodic arrays of pillars having diameters betweenfor example about 80 nm and about 250 nm and heights between for exampleabout 400 nm and 800 nm or between about 400 nm and 1 micron. The heightis chosen as a design parameter to optimize system performance,chromatic aberration and efficiency. The pitch (center to centerspacing) between rods may for be for example between 220 nm and 280 nm,which leaves a minimum gap between pillars of 30 nm. Such nanopillarsmay be arranged to form nano-gratings in concentric rings about acentral optical axis of the metalens, as described above, with the longaxes of the pillars arranged perpendicularly to the plane of the array.

Alternatively, the nanoantennas may be or comprise structures having finshapes, for example. Such fin shaped nanoantennas (nanofins) may be forexample similar in shape to pillars as described above but haveflattened cross-sections perpendicular to their long axes. Such nanofinsmay be arranged similarly to the arrangements of nanopillars describedabove. A metalens comprising nanofins may be designed to be polarizing,that is, to preferentially transmit light of a particular linearpolarization.

The height of the metalens can be reduced to the height of thenanoantennas (e.g., nanopillars or nanofins). This is substantiallythinner than conventional imaging optics which typically have athickness of 1 mm or more. For an imaging optic, such as a camera-flashlens, the periodic array may be disposed on a substrate that is spacedapart from the LED array. As noted above, for a camera flash lens themodulation transfer function may be less important than the illuminancewhich makes metalenses a suitable choice. Also, for a camera flash lensthe requirement for chromatic aberration will be less stringent than fora true imaging application. The efficiency, however, will be animportant parameter leading to large optics with highest possiblenumerical aperture (NA).

FIG. 3 shows an example of a possible arrangement of pillars 150 in anarray of nanoantennas in a metasurface 155 in a metalens. Nanofins couldbe similarly arranged. The metasurface 155 is made up of a periodicarrangement of unit cells (e.g., 155A, 155B) with each unit cellcomprising one or more pillars. In the simplest case, the unit cellconsists of a single individual pillar. However, to improve coloruniformity and to correct color aberration, the unit cell can consist ofmore than one pillar. For example, the unit cell can consist of threenanocylinders placed in a triangular lattice. Pillars within a unit cellcan have cross-sections that are, for example, circular, elliptical,square, or rectangular.

Referring again to FIG. 1 , in the illustrated example metalens 130comprises a transparent substrate 130S (sapphire, for example) having aplanar top surface 130T facing away from the LED array and a bottomsurface 130B facing the LED array. An array of nanoantennas may bearranged as a metasurface on surface 130T, on surface 130B, or onsurface 130T and on surface 130B to provide the desired lens function.

The placement of arrays of nanoantennas on both sides of the substratecan help with multiple aspects of the metalens design: 1) improving theefficiency by pre-collimating the incident light thereby increasingefficiency of the system by reducing the NA of the lens, and 2) improvethe imaging system performance by offering avenues to correct aberrationand color uniformity. Bending a beam at large angles is often lessefficient than at lower angles. Having arrays of nanoantennas on bothsides of the substrate may improve the efficiency, especially for theedges where large angles of deflection are needed.

In one variation, metalens 130 comprises arrays of nanoantennas on bothsides 130T and 130B of the substrate near edges of the metalens wherelarge deflection angles are needed, and an array of nanoantennas on onlyone side of the substrate (130T or 130B) in the central region of themetalens where the beam deflection is moderate.

To maximize efficiency an antireflective coating can be deposited onsurfaces of substrate 130 on which there are no metastructures. Forexample, a porous low index layer or a multi-layer stack can be used toimprove the incoupling of light. Other potential modifications includethe deposition of a low index material in between the pillars to improvethe mechanical robustness of the module. For a pure imaging optic, therecirculation of light should be avoided. Some recirculation for a flashlens could however be advantageous to increase efficiency. To this endadditional scattering coatings can be applied.

Referring now to example adaptive lighting system 400 shown in FIG. 4 ,to further maximize efficiency a pre-collimator 160 may be added to theadaptive lighting system shown in FIG. 1 . Pre-collimator 160 narrowsdown the angular emission of the LED array light source such thatmetalens 130 can be optimized and operate most effectively. This, inturn, should offer improvements in both power efficiency and lightsteering control, as well as a reduction in area of the lens up to 25%.Pre-collimator 160 may, for example, comprise a transparent substrate160S (sapphire, for example) having a planar top surface 160T facingaway from the LED array and a bottom surface 160B facing the LED array.An array of nanoantennas (pillars or fins as described above, forexample) may be arranged as a metasurface on surface 160T, on surface160B, or on surface 160T and on surface 130B to provide the desiredpre-collimating function. Note that the overall thickness of adaptivelighting system 400 need not be greater than that of adaptive lightingsystem 100 of FIG. 1 , provided that the target focal length distancewithout collimator is larger than the substrate thickness of thepre-collimator (neglecting metasurface thickness, i.e. <=1 um).

An important factor in obtaining high efficiency, low loss metalensesand pre-collimators is the choice of materials for the nanoantennas andthe way they are prepared. Using materials that have a high refractiveindex and low absorptive loss improves performance. The refractive indexand absorptive loss can depend on the way the material is prepared.Suitable materials for the nanoantennas may include, but are not limitedto, niobium pentoxide, gallium nitride, silicon nitride, titaniumdioxide, or hafnium oxide.

Metalenses as described herein are preferably prepared using sputtering(physical vapor deposition) or chemical vapor deposition to form ahomogenous layer of the nanoantenna material. Gallium nitride (GaN),niobium pentoxide (Nb₂O₅), and silicon nitride are suitable materials tobe used in this approach. For these materials immersion DUV, oralternatively nanoimprinting patterning techniques, can be subsequentlyused to pattern the layer to form nanoantenna arrays, followed byanisotropic etching in which a hard mask may be used to have a definedetch stop, leading to a well-defined layer thickness (e.g., pillar orfin height).

A less preferable approach is to write a pattern with e-beam lithographyinto a e-beam resist, and then subsequently fill the pattern withniobium pentoxide using atomic layer deposition (ALD). Due to the natureof the resist, the ALD can only be performed at low temperature and thishas consequences for the refractive index of the material. It is knownthat niobium pentoxide prepared by ALD has a refractive index at 550 nmbelow 2.2, while bulk niobium pentoxide has a refractive index of 2.36.In contrast, niobium pentoxide formed by physical or chemical vapordeposition may have an index of refraction of 2.34 very close to thebulk value. This makes the sputtering approach preferable.

Further, with respect to losses by absorption the low temperature ALDgrowth approach is not optimal. Titanium Oxide (TiO₂) grown at 80° C.has an absorption (k) of about 0.004 and a refractive index of 2.37. Forsputter-coated niobium pentoxide the refractive index is 2.34 as notedabove and the absorption (k) is 0.0002, more than a factor of 10 lowerthan for titanium oxide, while the refractive index is similar. Inaddition, titanium oxide can be photocatalytic and may for that reasonbe disfavored. Also, for the ALD approach excess material must be etchedaway, there is no stop layer, and how much is etched just depends on thetime, which leads to worse control over nanoantenna (e.g., pillar orfin) height.

FIG. 5 shows a cross-sectional view of an example adaptive lightingsystem 500 comprising an LED array 110, a pre-collimator 160, and ametalens 130. Metalens 130 comprises a metasurface 505T disposed on atop surface of a substrate 130S and a metasurface 505B disposed on abottom surface of substrate 130S. LED array 110 is disposed on asubstrate 510 in a cavity 515 defined by side reflectors 520 andpre-collimator 160. Side reflectors 520 may be formed from a volumereflective material such as, for example, titanium oxide particlesdispersed in silicone. Side reflectors 520 may optionally be replaced byabsorptive material if no light recycling is sought. The cavity may befilled with air or another transparent medium as filler material, forexample a low index silicone or a nanoporous material. Metalens 130 isspaced apart from pre-collimator 160 by side walls 530, which may beabsorptive.

Metalens metasurfaces 505T and 505B may comprise concentric rings ofnanoantennas (e.g., pillars or fins), as described above, with thenanoantennas formed from niobium pentoxide as also described above. Thepre-collimator may have a similar structure to the metalens, comprisingfor example niobium pentoxide pillars of, for example, radius 58 nm,height 250 nm, and period (pitch) 180 nm. The pre-collimator mayalternatively be implemented as a multi-layered thin filmcoating/photonic crystal, or a photonic crystal consisting of nano-rodsand nano-cones formed, for example, from niobium pentoxide and/orgallium nitride.

FIGS. 6 and 7 show plots of calculated transmission versus angle ofincidence, for light having a wavelength of 450 nm, for the metalens ina system as in FIG. 5 with the metalens formed from niobium pentoxidepillars as described above. FIG. 8 similarly shows reflectance versusangle of incidence for the metalens, for light having a wavelength of450 nm.

FIG. 9 schematically illustrates an example camera flash system 900comprising an LED array and metalens adaptive illumination system 902,which may be similar or identical to the systems described above. Flashsystem 900 also comprises an LED driver 906 that is controlled by acontroller 904, such as a microprocessor. Controller 904 may also becoupled to a camera 907 and to sensors 908, and operate in accordancewith instructions and profiles stored in memory 910. Camera 907 andadaptive illumination system 902 may be controlled by controller 904 tomatch their fields of view.

Sensors 908 may include, for example, positional sensors (e.g., agyroscope and/or accelerometer) and/or other sensors that may be used todetermine the position, speed, and orientation of system 900. Thesignals from the sensors 908 may be supplied to the controller 904 to beused to determine the appropriate course of action of the controller 904(e.g., which LEDs are currently illuminating a target and which LEDswill be illuminating the target a predetermined amount of time later).

In operation, illumination from some or all of the pixels of the LEDarray in 902 may be adjusted—deactivated, operated at full intensity, oroperated at an intermediate intensity. As noted above, beam focus orsteering of light emitted by the LED array in 902 can be performedelectronically by activating one or more subsets of the pixels, topermit dynamic adjustment of the beam shape without moving optics orchanging the focus of the lens in the lighting apparatus.

Adaptive light emitting matrix pixel arrays and lens systems such asdescribed herein may support various other beam steering or otherapplications that benefit from fine-grained intensity, spatial, andtemporal control of light distribution. These applications may include,but are not limited to, precise spatial patterning of emitted light frompixel blocks or individual pixels. Depending on the application, emittedlight may be spectrally distinct, adaptive over time, and/orenvironmentally responsive. The light emitting pixel arrays may providepre-programmed light distribution in various intensity, spatial, ortemporal patterns. Associated optics may be distinct at a pixel, pixelblock, or device level. An example light emitting pixel array mayinclude a device having a commonly controlled central block of highintensity pixels with an associated common optic, whereas edge pixelsmay have individual optics. In addition to flashlights, commonapplications supported by light emitting pixel arrays include videolighting, automotive headlights, architectural and area illumination,and street lighting.

Applications supported by the described adaptive light emitting pixelarrays include augmented (AR) or virtual reality (VR) headsets, glasses,or projectors. For example, FIG. 10 schematically illustrates an exampleAR/VR system 1000 that includes an adaptive light emitting array 1010,AR or VR display 1020, a light emitting array controller 1030, sensorsystem 1040, and system controller 1050. Control input is provided tothe sensor system 1040, while power and user data input is provided tothe system controller 1050. As will be understood, in some embodimentsmodules included in the AR/VR system 1000 can be compactly arranged in asingle structure, or one or more elements can be separately mounted andconnected via wireless or wired communication. For example, the lightemitting array 1010, AR or VR display 1020, and sensor system 1040 canbe mounted on a headset or glasses, with the light emitting controllerand/or system controller 1050 separately mounted.

In one embodiment, the light emitting array 1010 includes one or moreadaptive light emitting arrays, as described above for example, that canbe used to project light in graphical or object patterns that cansupport AR/VR systems. In some embodiments, arrays of microLEDs (μLEDsor uLEDs) can be used. MicroLEDs can support high density pixels havinga lateral dimension less than 100 μm by 100 μm. In some embodiments,microLEDs with dimensions of about 50 μm in diameter or width andsmaller can be used. Such microLEDs can be used for the manufacture ofcolor displays by aligning in close proximity microLEDs comprising red,blue and green wavelengths. In other embodiments, microLEDs can bedefined on a monolithic GaN or other semiconductor substrate, formed onsegmented, partially, or fully divided semiconductor substrate, orindividually formed or panel assembled as groupings of microLEDs. Insome embodiments, the light emitting array 1010 can include smallnumbers of microLEDs positioned on substrates that are centimeter scalearea or greater. In some embodiments, the light emitting array 1010 cansupport microLED pixel arrays with hundreds, thousands, or millions oflight emitting LEDs positioned together on centimeter scale areasubstrates or smaller. In some embodiments, microLEDs can include lightemitting diodes sized between 30 microns and 500 microns. The lightemitting array(s) 1010 can be monochromatic, RGB, or other desiredchromaticity. In some embodiments, pixels can be square, rectangular,hexagonal, or have curved perimeter. Pixels can be of the same size, ofdiffering sizes, or similarly sized and grouped to present largereffective pixel size. In some embodiments, separate light emittingarrays can be used to provide display images, with AR features beingprovided by a distinct and separate micro-LED array. In someembodiments, a selected group of pixels can be used for displayingcontent to the user while tracking pixels can be used for providingtracking light used in eye tracking. Content display pixels are designedto emit visible light, with at least some portion of the visible band(approximately 400 nm to 750 nm). In contrast, tracking pixels can emitlight in visible band or in the IR band (approximately 750 nm to 2,200nm), or some combination thereof. As an alternative example, thetracking pixels could operate in the 800 to 1000 nanometer range. Insome embodiments, the tracking pixels can emit tracking light during atime period that content pixels are turned off and are not displayingcontent to the user.

As will be understood, in some embodiments light emitting pixels andcircuitry supporting light emitting array 1010 can be packaged andoptionally include a submount or printed circuit board connected forpowering and controlling light production by semiconductor LEDs. Incertain embodiments, a printed circuit board supporting light emittingarray 1010 can also include electrical vias, heat sinks, ground planes,electrical traces, and flip chip or other mounting systems. The submountor printed circuit board may be formed of any suitable material, such asceramic, silicon, aluminum, etc. If the submount material is conductive,an insulating layer is formed over the substrate material, and the metalelectrode pattern is formed over the insulating layer. The submount canact as a mechanical support, providing an electrical interface betweenelectrodes on the light emitting array 1010 and a power supply, and alsoprovide heat sink functionality.

The AR/VR system 1000 can incorporate a wide range of optics in adaptivelight emitting array 1010 and/or AR/VR display 1020, for example tocouple light emitted by adaptive light emitting array 1010 into AR/VRdisplay 1020. Such optical elements can include for example metalensesand pre-collimators as described above for example. For AR/VRapplications the metalenses and pre-collimators may comprise nanofins asdescribed above and be designed to polarize the light they transmit.Optical elements can also or alternatively include apertures, filters, aFresnel lens, a convex lens, a concave lens, or any other suitableoptical element that affects the projected light from the light emittingarray 1010. Additionally, one or more of the optical elements can haveone or more coatings, including UV blocking or anti-reflective coatings.In some embodiments optics can be used to correct or minimize two-orthree dimensional optical errors including pincushion distortion, barreldistortion, longitudinal chromatic aberration, spherical aberration,chromatic aberration, field curvature, astigmatism, or any other type ofoptical error. In some embodiments, optical elements can be used tomagnify and/or correct images. Advantageously, in some embodimentsmagnification of display images allows the light emitting array 1010 tobe physically smaller, of less weight, and require less power thanlarger displays. Additionally, magnification can increase a field ofview of the displayed content allowing display presentation equals auser's normal field of view.

In one embodiment, the light emitting array controller 1030 can be usedto provide power and real time control for the light emitting array1010. For example, the light emitting array controller 1030 can be ableto implement pixel or group pixel level control of amplitude and dutycycle. In some embodiments the light emitting array controller 1030further includes a frame buffer for holding generated or processedimages that can be supplied to the light emitting array 1010. Othersupported modules can include digital control interfaces such asInter-Integrated Circuit (I2C) serial bus, Serial Peripheral Interface(SPI), USB-C, HDMI, Display Port, or other suitable image or controlmodules that are configured to transmit needed image data, control dataor instructions.

In operation, pixels in the images can be used to define response ofcorresponding light emitting array 1010, with intensity and spatialmodulation of LED pixels being based on the image(s). To reduce datarate issues, groups of pixels (e.g. 5×5 blocks) can be controlled assingle blocks in some embodiments. In some embodiments, high speed andhigh data rate operation is supported, with pixel values from successiveimages able to be loaded as successive frames in an image sequence at arate between 30 Hz and 100 Hz, with 60 Hz being typical. Pulse widthmodulation can be used to control each pixel to emit light in a patternand with an intensity at least partially dependent on the image.

In some embodiments, the sensor system 1040 can include external sensorssuch as cameras, depth sensors, or audio sensors that monitor theenvironment, and internal sensors such as accelerometers or two or threeaxis gyroscopes that monitor AR/VR headset position. Other sensors caninclude but are not limited to air pressure, stress sensors, temperaturesensors, or any other suitable sensors needed for local or remoteenvironmental monitoring. In some embodiments, control input can includedetected touch or taps, gestural input, or control based on headset ordisplay position. As another example, based on the one or moremeasurement signals from one or more gyroscope or position sensors thatmeasure translation or rotational movement, an estimated position ofAR/VR system 1000 relative to an initial position can be determined.

In some embodiments, the system controller 1050 uses data from thesensor system 1040 to integrate measurement signals received from theaccelerometers over time to estimate a velocity vector and integrate thevelocity vector over time to determine an estimated position of areference point for the AR/VR system 1000. In other embodiments, thereference point used to describe the position of the AR/VR system 1000can be based on depth sensor, camera positioning views, or optical fieldflow.

Based on changes in position, orientation, or movement of the AR/VRsystem1000, the system controller 1050 can send images or instructionsthe light emitting array controller 1030. Changes or modification theimages or instructions can also be made by user data input, or automateddata input as needed. User data input can include but is not limited tothat provided by audio instructions, haptic feedback, eye or pupilpositioning, or connected keyboard, mouse, or game controller.

This disclosure is illustrative and not limiting. Further modificationswill be apparent to one skilled in the art in light of this disclosureand are intended to fall within the scope of the appended claims.

What is claimed is:
 1. An adaptive illumination system comprising: an array of independently controllable LEDs; a pre-collimator arranged to partially collimate light emitted by the LEDs; and a metalens positioned on an opposite side of the pre-collimator from the LEDs and comprising at least a first array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of the light partially collimated by the pre-collimator to further collimate the light, the metalens being positioned and structurally arranged so that light emitted from different LEDs of the array is directed to corresponding differing predefined far-field regions.
 2. The adaptive illumination system of claim 1, wherein each LED is a segment of a monolithic structure.
 3. The adaptive illumination system of claim 2, wherein each LED has dimensions in a plane of the array of less than or equal to 500 microns.
 4. The adaptive illumination system of claim 3, wherein each LED has dimensions in the plane of the array of less than or equal to 100 microns.
 5. The adaptive illumination system of claim 1, wherein the pre-collimator comprises an array of nanoantennas arranged to affect phase and amplitude of the light emitted by the LEDs to partially collimate the light.
 6. The adaptive illumination system of claim 5, wherein the nanoantennas in the pre-collimator are formed from niobium pentoxide, gallium nitride, silicon nitride, titanium dioxide, or hafnium oxide.
 7. The adaptive illumination system of claim 6, wherein the nanoantennas in the pre-collimator are formed from niobium pentoxide.
 8. The adaptive illumination system of claim 1, wherein the metalens comprises a substrate, and the first array of niobium pentoxide nanoantennas is arranged on a first surface of the substrate.
 9. The adaptive illumination system of claim 8, comprising a second array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of the light partially collimated by the pre-collimator to further collimate the light, the second array of niobium pentoxide nanoantennas arranged on a second surface of the substrate opposite from the first surface of the substrate.
 10. The adaptive illumination system of claim 1, wherein the niobium pentoxide nanoantennas have cylindrical shapes and are arranged with their long axes perpendicular to a plane of the metalens.
 11. The adaptive light illumination system of claim 1, wherein each LED is a segment of a monolithic structure, the metalens comprises a substrate, and the first array of niobium pentoxide nanoantennas is arranged on a first surface of the substrate, comprising a second array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of the light partially collimated by the pre-collimator to further collimate the light, the second array of niobium pentoxide nanoantennas arranged on a second surface of the substrate opposite from the first surface of the substrate.
 12. An adaptive illumination system comprising: an array of independently controllable LEDs; and a metalens spaced apart from the array of LEDs and comprising: a substrate; a first array of niobium pentoxide nanoantennas arranged on a first surface of the substrate to affect phase and amplitude of light emitted by the LEDs to partially collimated the light; and a second array of niobium pentoxide nanoantennas arranged on a second surface of the substrate opposite from the first surface to affect phase and amplitude of light emitted by the LEDs to further collimate the light, the metalens being positioned and structurally arranged so that light emitted from different LEDs of the array is directed to corresponding differing predefined far-field regions.
 13. An adaptive illumination system comprising: an array of independently controllable LEDs; and a metalens spaced apart from the array of LEDs, the metalens comprising: a substrate; a first array of niobium pentoxide nanoantennas arranged on a first surface of the substrate to affect phase and amplitude of light emitted by the LEDs to partially collimated the light; and a second array of niobium pentoxide nanoantennas arranged on a second surface of the substrate opposite from the first surface to affect phase and amplitude of light emitted by the LEDs to further collimate the light, wherein: both the first and the second array of niobium pentoxide nanoantennas extend to outer portions of the metalens; the first array of niobium pentoxide nanoantennas covers central regions of the metalens around an optical axis of the metalens; and the second array of niobium pentoxide nanoantennas does not cover the central region of the metalens.
 14. The adaptive illumination system of claim 13, wherein each LED is a segment of a monolithic structure.
 15. The adaptive illumination system of claim 14, wherein each LED has dimensions in a plane of the array of less than or equal to 500 microns.
 16. The adaptive illumination system of claim 15, wherein each LED has dimensions in the plane of the array of less than or equal to 100 microns.
 17. The adaptive illumination system of claim 12, wherein the niobium pentoxide nanoantennas have cylindrical shapes and are arranged with their long axes perpendicular to a plane of the metalens.
 18. A mobile device comprising: a camera; a flash illumination system comprising: a monolithic array of independently controllable LEDs; a metalens spaced apart from the array of LEDs and comprising at least a first array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of light emitted by the LEDs to at least partially collimate the light, the metalens being positioned and structurally arranged so that light emitted from different LEDs of the array is directed to corresponding differing predefined far-field regions; and a controller configured to operate the LEDs to match a field of view of the flash illumination system to a field of view of the camera.
 19. The mobile device of claim 18, wherein each LED has dimensions in a plane of the array of less than or equal to 500 microns.
 20. The mobile device of claim 18, wherein the metalens comprises a substrate, and the first array of niobium pentoxide nanoantennas is arranged on a first surface of the substrate.
 21. The mobile device of claim 20, comprising a second array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of the light emitted by the LEDs to at least partially collimate the light, the second array of niobium pentoxide nanoantennas arranged on a second surface of the substrate opposite from the first surface of the substrate.
 22. The mobile device of claim 18, comprising a pre-collimator positioned between the LED array and the metalens in an optical path of light emitted by the array of LEDs.
 23. A display system comprising: a display; a monolithic array of independently controllable LEDs; and a metalens spaced apart from the array of LEDs and arranged to couple light from the array of LEDs into the display, the metalens comprising at least a first array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of light emitted by the LEDs to at least partially collimate the light, the metalens being positioned and structurally arranged so that light emitted from different LEDs of the array is directed to corresponding differing predefined far-field regions.
 24. The display system of claim 23, wherein each LED has dimensions in a plane of the array of less than or equal to 100 microns.
 25. The display system of claim 23, wherein the metalens comprises a substrate, and the first array of niobium pentoxide nanoantennas is arranged on a first surface of the substrate.
 26. The display system of claim 25, comprising a second array of niobium pentoxide nanoantennas arranged to affect phase and amplitude of the light emitted by the LEDs to at least partially collimate the light, the second array of niobium pentoxide nanoantennas arranged on a second surface of the substrate opposite from the first surface of the substrate.
 27. The display system of claim 23, comprising a pre-collimator positioned between the LED array and the metalens in an optical path of light emitted by the array of LEDs. 